docs: def make_spo(sub, prd, obj):
      '''
      Decorates the three given strings as a line of ntriples
  
      '''
      # To establish string as a curie and expand,
      # we use a global curie_map(.yaml)
      # sub are allways uri  (unless a bnode)
      # prd are allways uri (unless prd is 'a')
      # should fail loudly if curie does not exist
      if prd == 'a':
          prd = 'rdf:type'
  
      try:
          (subcuri, subid) = re.split(r':', sub)
      except Exception:
          LOG.error("not a Subject Curie  '%s'", sub)
          raise ValueError
  
      try:
          (prdcuri, prdid) = re.split(r':', prd)
      except Exception:
          LOG.error("not a Predicate Curie  '%s'", prd)
          raise ValueError
      objt = ''
  
      # object is a curie or bnode or literal [string|number]
  
      objcuri = None
      match = re.match(CURIERE, obj)
      if match is not None:
          try:
              (objcuri, objid) = re.split(r':', obj)
          except ValueError:
              match = None
      if match is not None and objcuri in CURIEMAP:
          objt = CURIEMAP[objcuri] + objid.strip()
          # allow unexpanded bnodes in object
          if objcuri != '_' or CURIEMAP[objcuri] != '_:b':
              objt = '<' + objt + '>'
      elif obj.isnumeric():
          objt = '"' + obj + '"'
      else:
          # Literals may not contain the characters ", LF, CR '\'
          # except in their escaped forms. internal quotes as well.
          obj = obj.strip('"').replace('\\', '\\\\').replace('"', '\'')
          obj = obj.replace('\n', '\\n').replace('\r', '\\r')
          objt = '"' + obj + '"'
  
      # allow unexpanded bnodes in subject
      if subcuri is not None and subcuri in CURIEMAP and \
              prdcuri is not None and prdcuri in CURIEMAP:
          subjt = CURIEMAP[subcuri] + subid.strip()
          if subcuri != '_' or CURIEMAP[subcuri] != '_:b':
              subjt = '<' + subjt + '>'
  
          return subjt + ' <' + CURIEMAP[prdcuri] + prdid.strip() + '> ' + objt + ' .'
      else:
          LOG.error(
              'Cant work with: <%s> %s , <%s> %s, %s',
              subcuri, subid, prdcuri, prdid, objt)
          return None